It has been previously shown that the birth weight of a mother influences the birth weight of her children. Presumably, small infants of small mothers are normal but small infants of large mothers are not. If such were the case, then small infants of small mothers can be expected to have a greater probability of survival than small infants whose mothers were not small. The maternal birth weight of all low birth weight infants in the Collaborative Perinatal Project will be entered, and analyses of this question will be done.